The present invention relates to an inner closure cap adapted to be tightly fitted to an open end of a neck portion of a bottle or tube type container and covered by an outer closure cap detachably mounted on the neck portion.
An inner closure cap of this kind is employed generally in small containers for receiving liquid or semifluid material such as cosmetics, foodstuffs, pharmaceuticals or the like and is provided with a pouring hole which has a diameter smaller than that of the open end of the container in order to permit the liquid or semifluid material to flow out little by little. The pouring hole is usually sealed by a removable sheet member so that the material may be prevented from leakage or deterioration before a user removes the sheet member. The sheet member is also intended to assure that the material in the container has not been used at all after filling thereof until delivered to the user. Thus, the sheet member must be secured to the inner cap so as not to peel off from the cap body during the transportation and display of the products but so as to permit easy removal thereof when desired.
FIG. 1 illustrates a known inner closure cap 1 which comprises a cap body 2 and a sheet member 6 for sealing a pouring hole 5. The cap body 2 has outer and inner sleeves 3 and 4 between which a neck portion of a container is to be fitted. The sheet member 6 is adhered to the flat upper surface of the cap body 2 and may be removed therefrom by pulling a tongue 7 formed integrally with the member 6. In this inner closure cap 1, however, since both of the sheet member 6 and the upper surface of the body 2 are flat, a small adhesive strength therebetween would result in peeling off or slipping of the member 6 when the inner cap 1 is fitted to the container or when an outer cap (not shown) is rotated for engagement and disengagement. To avoid this, if the adhesive strength is increased then the sheet member 6 is apt to break off at the time of removal, thereby causing inconvenience to the user.
The cap body 2 is usually formed of synthetic resin material which tends to contract after molding. Such contraction makes the adhesion of the member 6 to the body 2 loose, increasing a possibility of undesired peeling off of the member 6. Another factor of raising such possibility is an internal pressure which is generated by expansion of the material and a gas in the container during, for example, the display of the products at a high temperature. When such internal pressure is generated and applied to the outer cap through the sheet member 6, to open the outer cap sometimes destroys the seal.
Accordingly, an object of the present invention is to provide an inner closure cap for a bottle or tube type container, in which a seal of a pouring hole may be securely maintained until a user removes it and in which the removal of the seal may be easily carried out without the possibility of breaking of the seal.
Another object of the present invention is to provide an inner closure cap of the type set forth above, wherein an area for adhesion of the seal to a cap body may be increased particularly in a vertical direction thereby to obtain additional resistance against an internal pressure of the container.